Appendix VI.
Height of neutral axis from H = —^ = 275
24*57
io8r
bh*
Using the general formula I., =------1- ax"
2nd moment of n = 31-----+ ^-$ x 36) = 126*29
8xrs3 /
A = -j2 +(12x2-75) = 32-44
H =. * *? 5 + (7*5 x i'75a) = 57'S
b/fi
2nd moment of c = — + ax1
36
- 'S^6'S8 + (i'87x-S3) = 6-26
Total value of 2nd moment = 22279
.-. Moment of resistance = A ~~
JFt •
I'2^X222'8
= -^~~ == 79 ton ins.
O D
The wrought-iron beam has the neutral axis at its centre.
We will therefore take the 2nd moment of j + E 4- F and
double it, afterwards adding that of G.
2nd moment of j
7 x X'5
-^
+(3'5X4*752) = '79*073
E = till. 4. (2-25x4-252)
12
'C X *\
2nd moment of G = -3....P
12
5S +
Doubled
Total value of 2nd moment =
. •. Moment of resistance = /t -
= 5 -.9^5. ._ 292 tons ins.
= 24*02
143-640
287-28
J'2
292*48